Factors which exert the greatest influence on the selection of boilers are fuel characteristics, capacity and steam conditions, space conditions, cost and individual preference. FUEL CHARACTERISTICS Prior to a preliminary selection of equipment, complete information should be available concerning fuels on which boiler types and predicted performance are based. Numbers 5 and 6 fuel oil…
Cast iron boilers are suitable for steam generation or hot water heating where low pressures are used. They may be applied in commercial and industrial buildings within the capacity range available. The capacities of cast iron and steel boilers overlap. Where this occurs, any comparison should include the following: Steel boilers in the larger sizes…
Boilers may be classified in two general groups: 1. Sectional cast iron boilers. 2. Steel firebox boilers, fire-tube or water-tube. Cast iron boilers may be rectangular (or square) with vertical sections or round with horizontal sections. These boilers are usually shipped in sections and assembled at the place of installation. Some smaller boilers are factory-assembled.…
With the exception of the reciprocating and rotary compressors, the equipment considered is of the centrifugal type (fans, refrigeration compressors, pumps) operating at starting within a system of high and low sides that are equalized. Ordinarily no specific requirement of starting torque other than normal is needed. At times with large centrifugal compressors or fans…
EQUIPMENT SERVED The air conditioning and refrigeration systems include fans, pumps, and reciprocating, rotary and centrifugal compressors. To effect the transfer or compression of various liquids and gases such as air, water, brine of refrigerants, it is necessary to put this equipment into motion by prime movers, in this instance, electric motors. Apart from the…
Compressors may be classified as either open or hermetic. OPEN COMPRESSOR An open compressor requires an external drive and may be direct driven thru a coupling or belt driven to operate at a specific speed, depending on load requirements. The type of the drive (electric motor, internal combustion engine or steam turbine) may be selected…
Frequently, a motor will fail to start when powered up after an idle period. It may or may not make an audible hum, or it can trip the overcurrent device. To begin, check to see if there is power and if the guard or a fan blade has become bent so that the fan cannot…
A far better way was developed. Solderless connectors (“wire nuts”) make for a more efficient workflow and, if properly deployed, result in quality connections every time. An additional advantage is that for testing or alterations, the wire nut can be removed and replaced easily. Soldering is still essential in electrical work although it is used…
There are other concerns as well. For high-frequency signals, probe capacitance becomes critical, and there is the whole matter of impedance matching so that you do not have a chaotic mix of harmful reflections. There are many variations in the ways that an oscilloscope has to be set up, depending on the make and model…
Actually, any conductor has inductance, whether it is an ionized channel blasted across the sky by a lightning bolt or a nerve cell axon within your brain. However, usually we are talking about a segment of copper wire. Winding it to form a coil multiplies the inductance, and if these windings encircle a core made…
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